Method for transmitting and receiving control information for device-to-device (d2d) communication in wireless communication system and apparatus therefor

ABSTRACT

A method of transmitting uplink data, by a user equipment (UE) in a wireless communication system is discussed. The method includes receiving a physical downlink control channel (PDCCH), which is scrambled with a semi-persistent scheduling (SPS)—radio network temporary identifier (RNTI) (SPS-RNTI) and includes a downlink control information (DCI) format 0; validating an SPS uplink scheduling assignment based on the received PDCCH; and transmitting the uplink data based on the SPS uplink scheduling assignment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Continuation of co-pending U.S. patent applicationSer. No. 16/017,470 filed on Jun. 25, 2018, which is a Continuation ofU.S. patent application Ser. No. 15/032,915 filed on Apr. 28, 2016 (nowU.S. Pat. No. 10,028,264 issued on Jul. 17, 2018), which is the NationalPhase of PCT International Application No. PCT/KR2014/010287 filed onOct. 30, 2014, which claims the priority benefit under 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/897,821 filed on Oct. 30,2013, all of which are hereby expressly incorporated by reference intothe present application.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a wireless communication system, andmore particularly, to a method of transmitting and receiving controlinformation for D2D communication in a wireless communication system andan apparatus therefor.

Discussion of the Related Art

A 3rd generation partnership project long term evolution (3GPP LTE)(hereinafter, referred to as ‘LTE’) communication system which is anexample of a wireless communication system to which the presentinvention can be applied will be described in brief.

FIG. 1 is a diagram illustrating a network structure of an EvolvedUniversal Mobile Telecommunications System (E-UMTS) which is an exampleof a wireless communication system. The E-UMTS is an evolved version ofthe conventional UMTS, and its basic standardization is in progressunder the 3rd Generation Partnership Project (3GPP). The E-UMTS may bereferred to as a Long Term Evolution (LTE) system. Details of thetechnical specifications of the UMTS and E-UMTS may be understood withreference to Release 7 and Release 8 of “3rd Generation PartnershipProject; Technical Specification Group Radio Access Network.”

Referring to FIG. 1, the E-UMTS includes a User Equipment (UE), basestations (eNode B; eNB), and an Access Gateway (AG) which is located atan end of a network (E-UTRAN) and connected to an external network. Thebase stations may simultaneously transmit multiple data streams for abroadcast service, a multicast service and/or a unicast service.

One or more cells exist for one base station. One cell is set to one ofbandwidths of 1.44, 3, 5, 10, 15 and 20 MHz to provide a downlink oruplink transport service to several user equipments. Different cells maybe set to provide different bandwidths. Also, one base station controlsdata transmission and reception for a plurality of user equipments. Thebase station transmits downlink (DL) scheduling information of downlinkdata to the corresponding user equipment to notify the correspondinguser equipment of time and frequency domains to which data will betransmitted and information related to encoding, data size, and hybridautomatic repeat and request (HARQ). Also, the base station transmitsuplink (UL) scheduling information of uplink data to the correspondinguser equipment to notify the corresponding user equipment of time andfrequency domains that can be used by the corresponding user equipment,and information related to encoding, data size, and HARQ. An interfacefor transmitting user traffic or control traffic may be used between thebase stations. A Core Network (CN) may include the AG and a network nodeor the like for user registration of the user equipment. The AG managesmobility of the user equipment on a Tracking Area (TA) basis, whereinone TA includes a plurality of cells.

Although the wireless communication technology developed based on WCDMAhas been evolved into LTE, request and expectation of users andproviders have continued to increase. Also, since another wirelessaccess technology is being continuously developed, new evolution of thewireless communication technology will be required for competitivenessin the future. In this respect, reduction of cost per bit, increase ofavailable service, use of adaptable frequency band, simple structure andopen type interface, proper power consumption of the user equipment,etc. are required.

A terminal periodically and/or aperiodically reports information on acurrent channel state to a base station to assist efficient managementof a wireless communication system of the base station. Since theinformation on the channel state reported to the base station is able toinclude results calculated in consideration of various situations, amore efficient reporting method is required.

SUMMARY OF THE INVENTION

An object of the preset invention is to provide a method of transmittingand receiving control information for D2D communication in a wirelesscommunication system and an apparatus therefor based on theaforementioned discussion.

Technical tasks obtainable from the present invention are non-limitedthe above-mentioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, accordingto one embodiment, a method of receiving control information, which isreceived by a user equipment (UE) for a D2D (device-to-device) ProSe ina wireless communication system, includes the steps of receivinginformation on radio resources semi-statically configured for the D2DProSe (device-to-device proximity service) and receiving a downlinkcontrol information (DCI) for indicating whether to activate the D2DProSe on a specific radio resource among the radio resources. In thiscase, the downlink control information is valid only in a discoveryprocedure to which a resource for UE-specifically transmitting adiscovery signal is allocated.

Moreover, a length of a DCI format associated with the downlink controlinformation may correspond to a length equal to or less than apredetermined length.

Moreover, a length of a DCI format associated with the downlink controlinformation can be determined according to a bandwidth configured forthe D2D ProSe.

Moreover, whether to activate the D2D ProSe can be indicated using aresource block assignment field of a DCI format used for determiningwhether to activate semi-persistent scheduling. Preferably, the specificradio resource can be indicated by an index of a D2D resource unit usingthe resource block assignment field. Or, a size of the resource blockassignment field can be determined according to a system bandwidth. Theresource block assignment field is configured by first bits and secondbits, the first bits are used for indicating an index of a D2D resourceunit and the second bits are used for indicating a D2D discoverysubframe.

Moreover, either a procedure of transmitting and receiving a D2Ddiscovery signal or a procedure of transmitting and receiving a D2Dcommunication signal can be determined according to a position of thespecific radio resource.

Moreover, whether to activate the D2D ProSe can be indicated byredefining a specific field among fields of a DCI format used fordetermining whether to activate semi-persistent scheduling.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a different embodiment, auser equipment receiving control information for a D2D(device-to-device) ProSe in a wireless communication system includes anRF (radio frequency) unit and a processor, the processor configured toreceive information on radio resources semi-statically configured forthe D2D ProSe (device-to-device proximity service), the processorconfigured to receive a downlink control information (DCI) forindicating whether to activate the D2D ProSe on a specific radioresource among the radio resources. In this case, the downlink controlinformation is valid only in a discovery procedure to which a resourcefor UE-specifically transmitting a discovery signal is allocated.

According to embodiments of the present invention, it is able toefficiently transmit and receive control information for D2Dcommunication in a wireless communication system.

Effects obtainable from the present invention may be non-limited by theabove mentioned effect. And, other unmentioned effects can be clearlyunderstood from the following description by those having ordinary skillin the technical field to which the present invention pertains.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a schematic diagram of E-UMTS network structure as one exampleof a wireless communication system;

FIG. 2 is a diagram illustrating structures of a control plane and auser plane of a radio interface protocol between a user equipment andE-UTRAN based on the 3GPP radio access network standard;

FIG. 3 is a diagram illustrating physical channels used in a 3GPP LTEsystem and a general method for transmitting a signal using the physicalchannels;

FIG. 4 is a diagram illustrating a structure of a radio frame used in anLTE system;

FIG. 5 is a diagram of a resource grid for a downlink slot;

FIG. 6 is a diagram for an example of a structure of a downlinksubframe;

FIG. 7 is a diagram for an example of a structure of an uplink subframein LTE;

FIG. 8 is a diagram for explaining D2D (UE-to-UE) communication;

FIG. 9 is a diagram for explaining scenarios for performing D2Dcommunication;

FIG. 10 is a diagram for explaining a resource configuration of aUE-specific D2D discovery signal (i.e., D2D discovery signal of a type2); and

FIG. 11 is a diagram for a base station and a user equipment capable ofbeing applied to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following technology may be used for various wireless accesstechnologies such as CDMA (code division multiple access), FDMA(frequency division multiple access), TDMA (time division multipleaccess), OFDMA (orthogonal frequency division multiple access), andSC-FDMA (single carrier frequency division multiple access). The CDMAmay be implemented by the radio technology such as UTRA (universalterrestrial radio access) or CDMA2000. The TDMA may be implemented bythe radio technology such as global system for mobile communications(GSM)/general packet radio service (GPRS)/enhanced data rates for GSMevolution (EDGE). The OFDMA may be implemented by the radio technologysuch as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, andevolved UTRA (E-UTRA). The UTRA is a part of a universal mobiletelecommunications system (UMTS). A 3rd generation partnership projectlong term evolution (3GPP LTE) is a part of an evolved UMTS (E-UMTS)that uses E-UTRA, and adopts OFDMA in a downlink and SC-FDMA in anuplink. LTE-advanced (LTE-A) is an evolved version of the 3GPP LTE.

For clarification of the description, although the following embodimentswill be described based on the 3GPP LTE/LTE-A, it is to be understoodthat the technical spirits of the present invention are not limited tothe 3GPP LTE/LTE-A. Also, specific terminologies hereinafter used in theembodiments of the present invention are provided to assistunderstanding of the present invention, and various modifications may bemade in the specific terminologies within the range that they do notdepart from technical spirits of the present invention.

FIG. 2, including view (a) and view (b), is a diagram illustratingstructures of a control plane and a user plane of a radio interfaceprotocol between a user equipment and E-UTRAN based on the 3GPP radioaccess network standard. In FIG. 2(a), the control plane means apassageway where control messages are transmitted, wherein the controlmessages are used by the user equipment and the network to manage call.In FIG. 2(b), the user plane means a passageway where data generated inan application layer, for example, voice data or Internet packet dataare transmitted.

A physical layer as the first layer provides an information transferservice to an upper layer using a physical channel. The physical layeris connected to a medium access control (MAC) layer via a transportchannel, wherein the medium access control layer is located above thephysical layer. Data are transferred between the medium access controllayer and the physical layer via the transport channel. Data aretransferred between one physical layer of a transmitting side and theother physical layer of a receiving side via the physical channel. Thephysical channel uses time and frequency as radio resources. In moredetail, the physical channel is modulated in accordance with anorthogonal frequency division multiple access (OFDMA) scheme in adownlink, and is modulated in accordance with a single carrier frequencydivision multiple access (SC-FDMA) scheme in an uplink.

A medium access control (MAC) layer of the second layer provides aservice to a radio link control (RLC) layer above the MAC layer via alogical channel. The RLC layer of the second layer supports reliabledata transmission. The RLC layer may be implemented as a functionalblock inside the MAC layer. In order to effectively transmit data usingIP packets such as IPv4 or IPv6 within a radio interface having a narrowbandwidth, a packet data convergence protocol (PDCP) layer of the secondlayer performs header compression to reduce the size of unnecessarycontrol information.

A radio resource control (RRC) layer located on the lowest part of thethird layer is defined in the control plane only. The RRC layer isassociated with configuration, re-configuration and release of radiobearers (‘RBs’) to be in charge of controlling the logical, transportand physical channels. In this case, the RB means a service provided bythe second layer for the data transfer between the user equipment andthe network. To this end, the RRC layers of the user equipment and thenetwork exchange RRC message with each other. If the RRC layer of theuser equipment is RRC connected with the RRC layer of the network, theuser equipment is in an RRC connected mode. If not so, the userequipment is in an RRC idle mode. A non-access stratum (NAS) layerlocated above the RRC layer performs functions such as sessionmanagement and mobility management.

One cell constituting a base station eNB is set to one of bandwidths of1.4, 3.5, 5, 10, 15, and 20 MHz and provides a downlink or uplinktransmission service to several user equipments. At this time, differentcells may be set to provide different bandwidths.

As downlink transport channels carrying data from the network to theuser equipment, there are provided a broadcast channel (BCH) carryingsystem information, a paging channel (PCH) carrying paging message, anda downlink shared channel (SCH) carrying user traffic or controlmessages. Traffic or control messages of a downlink multicast orbroadcast service may be transmitted via the downlink SCH or anadditional downlink multicast channel (MCH). Meanwhile, as uplinktransport channels carrying data from the user equipment to the network,there are provided a random access channel (RACH) carrying an initialcontrol message and an uplink shared channel (UL-SCH) carrying usertraffic or control message. As logical channels located above thetransport channels and mapped with the transport channels, there areprovided a broadcast control channel (BCCH), a paging control channel(PCCH), a common control channel (CCCH), a multicast control channel(MCCH), and a multicast traffic channel (MTCH).

FIG. 3 is a diagram illustrating physical channels used in a 3GPP LTEsystem and a general method for transmitting a signal using the physicalchannels.

The user equipment performs initial cell search such as synchronizingwith the base station when it newly enters a cell or the power is turnedon at step S301. To this end, the user equipment synchronizes with thebase station by receiving a primary synchronization channel (P-SCH) anda secondary synchronization channel (S-SCH) from the base station, andacquires information such as cell ID, etc. Afterwards, the userequipment may acquire broadcast information within the cell by receivinga physical broadcast channel (PBCH) from the base station. Meanwhile,the user equipment may identify a downlink channel status by receiving adownlink reference signal (DL RS) at the initial cell search step.

The user equipment which has finished the initial cell search mayacquire more detailed system information by receiving a physicaldownlink shared channel (PDSCH) in accordance with a physical downlinkcontrol channel (PDCCH) and information carried in the PDCCH at stepS302.

Afterwards, the user equipment may perform a random access procedure(RACH) such as steps S303 to S306 to complete access to the basestation. To this end, the user equipment may transmit a preamble througha physical random access channel (PRACH) (S303), and may receive aresponse message to the preamble through the PDCCH and the PDSCHcorresponding to the PDCCH (S304). In case of a contention based RACH,the user equipment may perform a contention resolution procedure such astransmission (S305) of additional physical random access channel andreception (S306) of the physical downlink control channel and thephysical downlink shared channel corresponding to the physical downlinkcontrol channel.

The user equipment which has performed the aforementioned steps mayreceive the physical downlink control channel (PDCCH)/physical downlinkshared channel (PDSCH) (S307) and transmit a physical uplink sharedchannel (PUSCH) and a physical uplink control channel (PUCCH) (S308), asa general procedure of transmitting uplink/downlink signals. Controlinformation transmitted from the user equipment to the base station willbe referred to as uplink control information (UCI). The UCI includesHARQ ACK/NACK (Hybrid Automatic Repeat and reQuestAcknowledgement/Negative-ACK), SR (Scheduling Request), CSI (ChannelState Information), etc. In this specification, the HARQ ACK/NACK willbe referred to as HARQ-ACK or ACK/NACK (A/N). The HARQ-ACK includes atleast one of positive ACK (simply, referred to as ACK), negative ACK(NACK), DTX and NACK/DTX. The CSI includes CQI (Channel QualityIndicator), PMI (Precoding Matrix Indicator), RI (Rank Indication), etc.Although the UCI is generally transmitted through the PUCCH, it may betransmitted through the PUSCH if control information and traffic datashould be transmitted at the same time. Also, the user equipment maynon-periodically transmit the UCI through the PUSCH in accordance withrequest/command of the network.

FIG. 4, including view (a) and view (b), is a diagram illustrating astructure of a radio frame used in an LTE system.

Referring to FIG. 4, in a cellular OFDM radio packet communicationsystem, uplink/downlink data packet transmission is performed in a unitof subframe, wherein one subframe is defined by a given time intervalthat includes a plurality of OFDM symbols. The 3GPP LTE standardsupports a type 1 radio frame structure applicable to frequency divisionduplex (FDD) and a type 2 radio frame structure applicable to timedivision duplex (TDD).

FIG. 4(a) is a diagram illustrating a structure of a type 1 radio frame.The downlink radio frame includes 10 subframes, each of which includestwo slots in a time domain. A time required to transmit one subframewill be referred to as a transmission time interval (TTI). For example,one subframe may have a length of Ims, and one slot may have a length of0.5 ms. One slot includes a plurality of OFDM symbols in a time domainand a plurality of resource blocks (RB) in a frequency domain. Since the3GPP LTE system uses OFDM in a downlink, OFDM symbols represent onesymbol interval. The OFDM symbol may be referred to as SC-FDMA symbol orsymbol interval. The resource block (RB) as a resource allocation unitmay include a plurality of continuous subcarriers in one slot.

The number of OFDM symbols included in one slot may be varied dependingon configuration of a cyclic prefix (CP). Examples of the CP include anextended CP and a normal CP. For example, if the OFDM symbols areconfigured by the normal CP, the number of OFDM symbols included in oneslot may be 7. If the OFDM symbols are configured by the extended CP,since the length of one OFDM symbol is increased, the number of OFDMsymbols included in one slot is smaller than that of OFDM symbols incase of the normal CP. For example, in case of the extended CP, thenumber of OFDM symbols included in one slot may be 6. If a channel stateis unstable like the case where the user equipment moves at high speed,the extended CP may be used to reduce inter-symbol interference.

If the normal CP is used, since one slot includes seven OFDM symbols,one subframe includes 14 OFDM symbols. At this time, first maximum threeOFDM symbols of each subframe may be allocated to a physical downlinkcontrol channel (PDCCH), and the other OFDM symbols may be allocated toa physical downlink shared channel (PDSCH).

FIG. 4(b) is a diagram illustrating a structure of a type 2 radio frame.The type 2 radio frame includes two half frames, each of which includesfour general subframes, which include two slots, and a special subframewhich includes a downlink pilot time slot (DwPTS), a guard period (GP),and an uplink pilot time slot (UpPTS).

In the special subframe, the DwPTS is used for initial cell search,synchronization or channel estimation at the user equipment. The UpPTSis used for channel estimation at the base station and uplinktransmission synchronization of the user equipment. In other words, theDwPTS is used for downlink transmission, whereas the UpPTS is used foruplink transmission. Especially, the UpPTS is used for PRACH preamble orSRS transmission. Also, the guard period is to remove interferenceoccurring in the uplink due to multipath delay of downlink signalsbetween the uplink and the downlink.

Configuration of the special subframe is defined in the current 3GPPstandard document as illustrated in Table 1 below. Table 1 illustratesthe DwPTS and the UpPTS in case of T_(s)=1/(15000×2048), and the otherregion is configured for the guard period.

TABLE 1 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Special subframe Normal cyclic Extended cyclicNormal cyclic Extended cyclic configuration DwPTS prefix in uplinkprefix in uplink DwPTS prefix in uplink prefix in uplink 0  6592 · T_(s)2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s) 119760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — —9 13168 · T_(s) — — —

In the meantime, the structure of the type 2 radio frame, that is,uplink/downlink configuration (UL/DL configuration) in the TDD system isas illustrated in Table 2 below.

TABLE 2 Uplink- Downlink- downlink to-Uplink config- Switch-pointSubframe number uration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U UD S U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 msD S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D DD D 6 5 ms D S U U U D S U U D

In the above Table 2, D means the downlink subframe, U means the uplinksubframe, and S means the special subframe. Also, Table 2 alsoillustrates a downlink-uplink switching period in the uplink/downlinksubframe configuration of each system.

The structure of the aforementioned radio frame is only exemplary, andvarious modifications may be made in the number of subframes included inthe radio frame, the number of slots included in the subframe, or thenumber of symbols included in the slot.

FIG. 5 is a diagram illustrating a resource grid of a downlink slot.

Referring to FIG. 5, the downlink slot includes a plurality of N_(symb)^(DL) OFDM symbols in a time domain and a plurality of N_(RB) ^(DL)resource blocks in a frequency domain. Since each resource blockincludes N_(sc) ^(RB) subcarriers, the downlink slot includes N_(RB)^(DL)×N_(sc) ^(RB) subcarriers in the frequency domain. Although FIG. 5illustrates that the downlink slot includes seven OFDM symbols and theresource block includes twelve subcarriers, it is to be understood thatthe downlink slot and the resource block are not limited to the exampleof FIG. 5. For example, the number of OFDM symbols included in thedownlink slot may be varied depending on the length of the CP.

Each element on the resource grid will be referred to as a resourceelement (RE). One resource element is indicated by one OFDM symbol indexand one subcarrier index. One RB includes N_(symb) ^(DL)×N_(sc) ^(RB)number of resource elements. The number N_(RB) ^(DL) of resource blocksincluded in the downlink slot depends on a downlink transmissionbandwidth configured in the cell.

FIG. 6 is a diagram illustrating a structure of a downlink subframe.

Referring to FIG. 6, maximum three (four) OFDM symbols located at thefront of the first slot of the subframe correspond to a control regionto which a control channel is allocated. The other OFDM symbolscorrespond to a data region to which a physical downlink shared channel(PDSCH) is allocated. Examples of downlink control channels used in theLTE system include a Physical Control Format Indicator Channel (PCFICH),a Physical Downlink Control Channel (PDCCH), and a Physical Hybrid ARQIndicator Channel (PHICH). The PCFICH is transmitted from the first OFDMsymbol of the subframe, and carries information on the number of OFDMsymbols used for transmission of the control channel within thesubframe. The PHICH carries HARQ ACK/NACK (Hybrid Automatic RepeatreQuest acknowledgement/negative-acknowledgement) signals in response touplink transmission.

The control information transmitted through the PDCCH will be referredto as downlink control information (DCI). The DCI includes resourceallocation information for a user equipment or user equipment group. Forexample, the DCI includes uplink/downlink scheduling information, uplinktransmission (Tx) power control command, etc.

The PDCCH may include transport format and resource allocationinformation of a downlink shared channel (DL-SCH), transport format andresource allocation information of an uplink shared channel (UL-SCH),paging information on a paging channel (PCH), system information on theDL-SCH, resource allocation information of upper layer control messagesuch as random access response transmitted on the PDSCH, a set oftransmission (Tx) power control commands of individual user equipments(UEs) within a random user equipment group, transmission (Tx) powercontrol command, and activity indication information of voice overInternet protocol (VoIP). A plurality of PDCCHs may be transmittedwithin the control region. The user equipment may monitor the pluralityof PDCCHs. The PDCCH is transmitted on aggregation of one or a pluralityof continuous control channel elements (CCEs). The CCE is a logicallocation unit used to provide the PDCCH with a coding rate based onthe status of a radio channel. The CCE corresponds to a plurality ofresource element groups (REGs). The format of the PDCCH and the numberof available bits of the PDCCH are determined depending on the number ofCCEs. The base station determines a PDCCH format depending on the DCIwhich will be transmitted to the user equipment, and attaches cyclicredundancy check (CRC) to the control information. The CRC is maskedwith an identifier (for example, radio network temporary identifier(RNTI)) depending on usage of the PDCCH or owner of the PDCCH. Forexample, if the PDCCH is for a specific user equipment, the CRC may bemasked with cell-RNTI (C-RNTI) of the corresponding user equipment. Ifthe PDCCH is for a paging message, the CRC may be masked with a pagingidentifier (for example, paging-RNTI (P-RNTI)). If the PDCCH is forsystem information (in more detail, system information block (SIB)), theCRC may be masked with system information RNTI (SI-RNTI). If the PDCCHis for a random access response, the CRC may be masked with a randomaccess RNTI (RA-RNTI).

In the following description, for the understanding of the presentinvention, a method of activating or deactivating (releasing) legacysemi-persistent scheduling (SPS) is explained. In particular, a basestation designates specific fields on a partial DCI format transmittedon a downlink control channel (e.g., PDCCH, EPDCCH) to a UE usingpredefined values to implicitly inform the UE of activation ordeactivation of the SPS.

In this case, the specific fields on the partial DCI format designatedby the predefined values can be utilized for a usage of a virtual CRC.By doing so, it is able to increase a ratio of successfully receivingcontrol information on the activation or the deactivation of the SPS.Moreover, the UE may attempt to detect a DCI format related to theactivation or the deactivation of the SPS using an SPS C-RNTI receivedfrom the base station in advance (i.e., The CRC parity bits obtained forthe PDCCH payload are scrambled with the Semi-Persistent SchedulingC-RNTI).

According to legacy LTE, it is able to inform a UE of subframes in whichSPS transmission/reception is to be performed via RRC (radio resourcecontrol) signaling for UL and/or DL SPS. In particular, a time resourceis preferentially designated via RRC signaling among time-frequencyresources allocated for the SPS. In order to notify a usable subframe,for example, it may be able to inform the UE of a period and an offsetof a usable subframe. Yet, since the UE receives allocation of a timeresource region only via the RRC signaling, although the UE receives theRRC signaling, the UE does not immediately perform transmission andreception scheduled by the SPS. Instead, the UE completes time-frequencyresource allocation by allocating a frequency resource region accordingto a necessity. When the frequency resource region is allocated, it maybe referred to as activation. On the contrary, when the frequencyresource region is released, it may be referred to as deactivation.

Hence, when the UE receives PDCCH for indicating the activation, the UEallocates a frequency resource according to RB allocation informationincluded in the received PDCCH, applies a modulation and a code rateaccording to MCS (modulation and coding scheme) information and startsto perform transmission and reception according to a subframe period andan offset assigned through the RRC signaling. Subsequently, if the UEreceives PDCCH for indicating the deactivation, from the base station,the UE terminates transmission and reception. If the UE receives PDCCHfor indicating activation and reactivation after the transmission andthe reception are terminated, the UE resumes transmission and receptionwith a subframe period and an offset assigned by RRC signaling using RBallocation, MCS and the like designated by the PDCCH. In particular,although a time resource is allocated through RRC signaling, a signalcan be actually transmitted and received after PDCCH for indicatingactivation and reactivation of the SPS is received. And, transmissionand reception of a signal can be terminated after PDCCH for indicatingdeactivation of the SPS is received.

A UE can check PDCCH including an SPS indication only if all thefollowing conditions are met. First of all, the CRC parity bits addedfor the PDCCH payload are scrambled with the SPS C-RNTI. Secondly, thenew data indicator (NDI) field is set to ‘0’. In this case, in case ofDCI formats 2, 2A, 2B, 2C and 2D, the new data indicator field refers tothe one for the enabled transport block.

And, a UE can check EPDCCH including an SPS indication only if all thefollowing conditions are met. First of all, the CRC parity bits addedfor the EPDCCH payload are scrambled with the SPS C-RNTI. Secondly, thenew data indicator (NDI) field is set to ‘0’. In this case, in case ofDCI formats 2, 2A, 2B, 2C and 2D, the new data indicator field refers tothe one for the enabled transport block.

Validation is achieved if all the fields for the respective used DCIformat are set according to Table 3 or Table 4. If validation isachieved, the UE shall consider the received DCI information accordinglyas a valid SPS activation or deactivation (release). On the contrary, ifvalidation is not achieved, the received DCI format shall be consideredby the UE as having been received with a non-matching CRC.

Table 3 in the following shows fields for validating PDCCH/EPDCCHindicating SPS activation.

TABLE 3 DCI format DCI format 0 DCI format 1/1A 2/2A/2B/2C/2D TPCcommand for scheduled PUSCH set to ‘00’ N/A N/A Cyclic shift DM RS setto ‘000’ N/A N/A Modulation and coding scheme MSB is set to ‘0’ N/A N/Aand redundancy version HARQ process number N/A FDD: set to ‘000’ FDD:set to ‘000’ TDD: set to ‘0000’ TDD: set to ‘0000’ Modulation and codingscheme N/A MSB is set to ‘0’ For the enabled transport block: MSB is setto ‘0’ Redundancy version N/A set to ‘00’ For the enabled transportblock: set to ‘00’

Table 4 in the following shows fields for validating PDCCH/EPDCCHindicating SPS deactivation (or release).

TABLE 4 DCI format 0 DCI format 1A TPC command for scheduled PUSCH setto ‘00’ N/A Cyclic shift DM RS set to ‘000’ N/A Modulation and codingscheme set to ‘11111’ N/A and redundancy version Resource blockassignment and Set to all ‘1’s N/A hopping resource allocation HARQprocess number N/A FDD: set to ‘000’ TDD: set to ‘0000’ Modulation andcoding scheme N/A set to ‘11111’ Redundancy version N/A set to ‘00’Resource block assignment N/A Set to all ‘1’s

If a DCI format indicates a SPS downlink scheduling activation, the TPCcommand for PUCCH field shall be used as an index to one of the fourPUCCH resource values configured by higher layers. Mapping relationbetween a TPC command and a PUCCH resource value is shown in Table 5 inthe following.

Table 5 shows a PUCCH resource value for downlink SPS scheduling.

TABLE 5 Value of ‘TPC command for PUCCH’ n_(PUCCH) ^((l,p)) ‘00’ Thefirst PUCCH resource value configured by the higher layers ‘01’ Thesecond PUCCH resource value configured by the higher layers ‘10’ Thethird PUCCH resource value configured by the higher layers ‘11’ Thefourth PUCCH resource value configured by the higher layers

FIG. 7 is a diagram for an example of a structure of an uplink subframein LTE.

Referring to FIG. 7, an uplink subframe includes a plurality of slots(e.g., 2 slots). A slot can include the different number of SC-FDMAsymbols depending on a CP length. An uplink subframe is divided into adata region and a control region in frequency domain. The data regionincludes PUSCH and is used for transmitting a data signal such as audioand the like. The control region includes PUCCH and is used fortransmitting uplink control information (UCI). PUCCH includes an RP pairpositioned at both ends of the data region in frequency axis and hops ata slot boundary.

PUCCH can be used for transmitting control information described in thefollowing.

-   -   SR (scheduling request): Information used for requesting uplink        UL-SCH resource. OOK (on-off keying) scheme is used to transmit        the SR.    -   HARQ ACK/NACK: Response signal for a DL data packet on PDSCH.        This information indicates whether or not a DL data packet is        successfully received. ACK/NACK 1 bit is transmitted in response        to a single DL codeword. ACK/NACK 2 bits are transmitted in        response to two DL codewords.    -   CSI (channel state information): Feedback information on a DL        channel. CSI includes a CQI (channel quality indicator) and MIMO        (multiple input multiple output)-related feedback information        includes an RI (rank indicator), a PMI (precoding matrix        indicator), a PTI (precoding type indicator) and the like. 20        bits per subframe are used.

An amount of control information (UCI) capable of being transmitted by auser equipment in a subframe is dependent on the number of SC-FDMAsavailable for transmitting control information. The SC-FDMAs availablefor transmitting the control information correspond to the remainingSC-FDMA symbols except SC-FDMA symbols used for transmitting a referencesignal in a subframe. In case of a subframe to which an SRS (soundingreference signal) is set, a last SC-FDMA symbol of a subframe is alsoexcluded. A reference signal is used for coherent detection of PUCCH.

In the following, D2D (UE-to-UE) communication is explained.

A D2D communication scheme can be mainly divided into a scheme ofreceiving the help from a network/coordination station (e.g., eNB) and ascheme of not receiving the help from the network/coordination station.

Referring to FIG. 8, FIG. 8(a) shows a scheme that anetwork/coordination station involves itself in transmitting andreceiving a control signal (e.g., a grant message), HARQ, channel stateinformation, and the like and data transmission and reception areperformed between UEs performing D2D communication only. FIG. 8(b) showsa scheme that a network provides minimum information (e.g., D2Dconnection information capable of being used in a corresponding cell) toUEs and the UEs performing D2D communication form a link and performdata transmission and reception.

In the following, a method for a specific UE to efficiently decode adiscovery signal (DS) in environment where D2D (device-to-device)communication is performed is explained based on the aforementioneddiscussion.

In the following, for clarity, the present invention is explained basedon 3GPP LTE system. However, a system range to which the presentinvention is applied can also be extended to a different system ratherthan the 3GPP LTE system. Embodiments of the present invention can beapplied not only to a case that a partial time resource region and/or apartial frequency resource region of a legacy system is allocated for ausage of D2D communication but also to a case that a new time resourceregion and/or a new frequency resource (different from a legacyresource) is (re)allocated for the D2D communication.

D2D communication can be mainly divided into two phases. The first phasecorresponds to “discovery phase” and a discovery signal istransmitted/received between D2D UEs in the discovery phase. In thiscase, a sequence of a discovery signal transmitted by a specific D2D UEcan be generated by a function with such an input variable as i) anidentifier (UE ID) of the D2D UE, ii) a group identifier (group ID),iii) a new identifier (new UE ID) assigned in advance, iv) atime/frequency resource index for transmitting a discovery signal andthe like. Hence, a random D2D UE can identify whether or not a differentD2D UE is adjacent to the random D2D UE based on a distance, whether ornot the different D2D UE is able to perform D2D data communication, andthe like.

The second phase of the D2D communication corresponds to a communicationphase. The communication phase includes i) an operation of actuallyperforming D2D data communication, ii) an operation of performingpreceding procedures predefined for stable D2D data communication (i.e.,“D2D link setup procedure” e.g., resource allocation, MCS configuration,power control, synchronization control, etc.) performed with thedifferent D2D UE identified by the first phase (i.e., discovery phase).

A concept of the D2D communication described in the foregoingdescription is just one of various D2D communication situations to whichthe present invention is applicable. The present invention described inthe following can be extensively applied to D2D communication situationof a different concept/configuration/scenario as well.

FIG. 9, including views (a), (b) and (c), is a diagram for examples ofvarious environment or scenarios in which D2D communication (e.g.,discovery phase and/or communication phase) is performed.

Referring to FIG. 9, D2D communication can be performed in a situationthat D2D UEs performing D2D communication are all positioned at theinside of network coverage as shown in FIG. 9(a), in a situation thatD2D UEs performing D2D communication are all positioned at the outsideof network coverage as shown in FIG. 9(b) and in a situation that that apart of D2D UEs performing D2D communication are positioned at theinside of network coverage and the remaining D2D UEs are positioned atthe outside of the network coverage as shown in FIG. 9(c).

And, a signal transmission/reception procedure required for thediscovery phase and/or the communication phase and a signal informationconfiguration can be differently defined according to individualenvironment or scenario of FIG. 9 (i.e., FIG. 9 (a) to FIG. 9(c)).

In the following, a type of a D2D discovery signal and a resourceconfiguration method are explained. Types of a D2D discovery signal andthe resource configuration method are shown in Table 6 in the following.

TABLE 6 The details of the two discovery types: [TYPE 1]: a discoveryprocedure where resources for discovery signal transmission areallocated on a non UE specific basis Note: Resources can be for all UEsor group of UEs [TYPE 2]: a discovery procedure where resources fordiscovery signal transmission are allocated on a per UE specific basis.TYPE 2A: Resources are allocated for each specific transmission instanceof discovery signals TYPE 2B: Resources are semi-persistently allocatedfor discovery signal transmission Discovery message transmissionresource configuration: Discovery message transmission resourceconfiguration consists of a number of subframes and a discovery period,and FFS a number of PRBs The number of discovery subframes and thediscovery period may be semi-statically configured at least when incoverage Individual discovery message transmission resources are not CDMAll individual discovery message transmission resources are the samesize

FIG. 10 is a diagram for explaining a concept for a resourceconfiguration of a type 2 D2D discovery signal shown in Table 6.Referring to FIG. 10, a predetermined amount of resources capable ofbeing used for the usage of transmitting/receiving a D2D discoverysignal is represented as a discovery resource group (DRG) and thepredetermined number of discovery subframes (DSF) and discovery resourceunits (DRU) are included in a specific discovery resource group. And,the predetermined number of discovery resource units exist in a specificdiscovery subframe and a specific discovery resource unit consists ofthe predetermined number of PRBs.

In this case, a size of a discovery resource unit used for transmittinga D2D discovery signal and a size of a discovery resource unit used fortransmitting D2D communication can be differently defined. Moreover, asize of a discovery resource unit can be configured to be changedaccording to a change of a system bandwidth or a change of a bandwidthconfigured for the usage of ProSe (D2D bandwidth). Or, it may define a(re)configuration operation (configurability) with regard to a size of adiscovery resource unit.

And, the predefined number of discovery resource groups exist on aspecific discovery period. In addition, it may be able to configure abase station to semi-statically or dynamically inform a UE of at leastone selected from the group consisting of i) a discovery periodconfiguration value, ii) the number of discovery resource groupsexisting on a specific discovery period, iii) the number of discoverysubframes and the number of discovery resource units existing on aspecific discovery resource group, iv) the number of discovery resourceunits existing on a specific discovery subframe, and v) the number ofPRBs constructing a specific discovery resource unit. Or, it may be ableto configure a specific D2D UE to semi-statically or dynamically informa different D2D UE of at least one selected from the group consisting ofi) a discovery period configuration value, ii) the number of discoveryresource groups existing on a specific discovery period, iii) the numberof discovery subframes and the number of discovery resource unitsexisting on a specific discovery resource group, iv) the number ofdiscovery resource units existing on a specific discovery subframe, andv) the number of PRBs constructing a specific discovery resource unitthrough a predefined signal.

In the following description, the present invention proposes a method ofefficiently notifying resource information to be used for transmitting aD2D signal (e.g., D2D discovery signal and/or D2D communication signal)on a DCI when initiation of transmitting the D2D signal (e.g., D2Ddiscovery signal and/or D2D communication signal) is activated ordeactivated by a predefined control channel (e.g., PDCCH, EPDCCH) in asituation that a resource related to a device-to-device proximityservice (D2D ProSe) (e.g., number/position of D2D SFs) issemi-statically or statically configured.

In the following description, the DCI according to embodiments of thepresent invention can be used for the usage of notifying resourceinformation to be used for receiving a D2D signal (e.g., a D2D discoverysignal and/or a D2D communication signal) when initiation of receivingthe D2D signal (e.g., D2D discovery signal and/or D2D communicationsignal) is activated or deactivated by a control channel in a situationthat a resource related to ProSe is semi-statically or staticallyconfigured.

And, it may be able to configure the embodiments of the presentinvention to be restrictively applied in a situation that a D2Ddiscovery signal of the aforementioned specific type (i.e., D2Ddiscovery signal type 2) is set and/or a specific environment in which aD2D communication signal is performed (i.e., D2D DS/CM within networkcoverage) only.

Additionally, the DCI according to the present invention can also beused for the usage of notifying resource information to be used fortransmitting/receiving a D2D signal (e.g., D2D discovery signal and/orD2D communication signal) when initiation of transmitting and receivingthe D2D signal (e.g., D2D discovery signal and/or D2D communicationsignal) is activated or deactivated by a predefined higher layer signalin a situation that a ProSe-related resource is semi-statically orstatically configured.

In the present invention, a DCI, which is transmitted to activate ordeactivate initiation of transmitting/receiving a D2D signal (e.g., aD2D discovery signal and/or a D2D communication signal), and a DCI,which is transmitted to notify resource information to be used fortransmitting and receiving a D2D signal (e.g., a D2D discovery signaland/or a D2D communication signal), can be independently defined,respectively.

Embodiment 1

A case of activating/deactivating initiation of transmitting a D2Dsignal by a predefined control channel in a situation that aProSe-related resource (e.g., number/position of D2D SFs) issemi-statically or statically configured is explained according to thefirst embodiment of the present invention. In this case, alength/structure of a DCI format, which is transmitted to notifyresource information related to transmission of the D2D signal (e.g.,D2D discovery signal and/or D2D communication signal), can be configuredto reuse a legacy DCI format (e.g., DCI format 0, DCI format 1A or DCIformat 1C) of a relatively short length (e.g., on the basis of apredefined or signaled specific value) to secure high reliability,prevent the number of performing blind decoding (BD) additionallyperformed by a UE from being increased or implement a simple controllingprocedure-based D2D ProSe.

For example, a D2D UE can be configured to detect at least one of i) aDCI format, which is transmitted to notify resource information relatedto transmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal) and ii) a DCI format, which is transmitted tonotify activation or deactivation of the initiation of transmitting aD2D signal (e.g., D2D discovery signal and/or D2D communication signal),based on a predetermined or signaled C-RNTI of the D2D UE, a temporaryC-RNTI, an SPS C-RNTI, or a D2D-RNTI newly configured or signaled forD2D usage.

As a different example, since an amount of bits required for notifyingresource information related to transmission of a D2D signal (e.g., D2Ddiscovery signal and/or D2D communication signal) varies according to achange of a system bandwidth or a change of a bandwidth (D2D bandwidth)configured for a ProSe usage, it is able to configure a length of a DCIformat, which is transmitted to notify the resource information relatedto the transmission of the D2D signal (e.g., D2D discovery signal and/orD2D communication signal), to be adaptively (re)configured(configurability).

Embodiment 2

In order to notify activation or deactivation of initiation oftransmitting a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal) or in order to notify resource information relatedto transmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal) in a situation that a ProSe-related resource(e.g., number/position of DS SF) is semi-statically or staticallyconfigured, it is able to configure i) a specific DCI format, which wasused for activating or deactivating a legacy SPS, to be reused, ii)partial fields of a specific DCI format to be used in a manner ofmodifying/aggregating/reinterpreting the partial fields or iii) valuesof partial fields (refer to Table 3 or Table 5), which are configured bya fixed value on a specific DCI format to notify activation/deactivationof a legacy SPS, to be used in a manner ofmodifying/aggregating/reinterpreting the partial fields. In this case, aD2D UE can be configured to detect at least one of i) a DCI format,which is transmitted to notify resource information related totransmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal) and ii) a DCI format, which is transmitted tonotify activation or deactivation of the initiation of transmitting aD2D signal (e.g., D2D discovery signal and/or D2D communication signal),based on a predetermined or signaled SPS C-RNTI of the D2D UE, a C-RNTI,a temporary C-RNTI, or a D2D-RNTI newly configured or signaled for D2Dusage.

As an example of the embodiment 2 of the present invention, it may beable to configure to reuse a resource block assignment (RBA) field of aspecific DCI format previously used for activating or deactivating alegacy SPS to notify resource information related to transmission of aD2D signal (e.g., D2D discovery signal and/or D2D communication signal).In other word, the resource information related to the transmission ofthe D2D signal (e.g., D2D discovery signal and/or D2D communicationsignal) can be defined by a form of notifying an index or a position ofa D2D resource unit (D2D RU) by reusing the resource block assignment(RBA) field of the specific DCI format previously used for activating ordeactivating the legacy SPS.

In this case, the D2D resource unit (D2D RU) index, which is indicatedby reusing the RBA field of the specific DCI format, can be configuredto perform re-indexing on all D2D RUs (e.g., in FIG. 10, all DRUspositioned on the predefined number of discovery subframes correspondingto a specific discovery resource group) positioned on the predeterminednumber and/or positions of D2D subframes in frequency-first direction ortime-first direction and use a corresponding result value.

Or, the D2D resource unit index, which is indicated by reusing the RBAfield of the specific DCI format, can be configured to perform indexingon all D2D RUs (e.g., in FIG. 10, all discovery resource unitspositioned on a specific discovery subframe) positioned on a specificD2D subframe in frequency-first direction or time-first direction anduse a corresponding result value. In particular, the aforementionedmethod can be comprehended as indexing is independently performed on aD2D resource unit according to a D2D subframe (e.g., in FIG. 10,indexing is independently performed on a discovery resource unitaccording to a discovery subframe).

As a further different example, a size of a resource block assignment(RBA) field on a legacy specific DCI format changes according to achange of a system bandwidth. However, if a D2D discovery signalusage-related bandwidth (DS bandwidth) and/or a D2D signal usage-relatedbandwidth is separately configured, it may be able to configure i)indexing for a D2D discovery signal-related resource unit (RU) and/orindexing for a D2D communication signal-related resource unit to beperformed on a system bandwidth or ii) indexing to be performed on a D2Ddiscovery signal usage-related bandwidth (and/or the D2D discoverysignal usage-related bandwidth to which indexing for a D2D discoverysignal-related resource unit (RU) and/or indexing for a D2Dcommunication signal-related resource unit is set.

In this case, the former method (i.e., indexing for a D2D discoverysignal-related resource unit is performed on a system bandwidth) can beapplied when a size of an RBA field on a specific DCI format is able tosufficiently satisfy the number of bits required to notify resourceinformation related to transmission of a D2D discovery signal (e.g., D2Ddiscovery signal and/or D2D communication signal). On the contrary, thelatter method (i.e., indexing for a D2D discovery signal-relatedresource unit is performed on a D2D discovery signal usage-relatedbandwidth) can be applied when a size of an RBA field on a specific DCIformat is unable to sufficiently satisfy the number of bits required tonotify resource information related to transmission of a D2D discoverysignal (i.e., it can also be comprehended as the D2D discovery signalusage-related bandwidth and/or the D2D discovery usage-related bandwidthis controlled in consideration of the size of the RBA field).

Table 7 in the following shows that sizes of the resource blockassignment (RBA) field of DCI formats used for activating ordeactivating legacy SPS vary according to a change of a system bandwidthon a legacy LTE wireless communication system. In this case, as anexample, a DCI format 0 assumes a case of “Non-hopping PUSCH withSingle-Cluster Allocation”, a DCI format 1A assumes a case of “LocalizedVRB” and DCI format 1/1A/2/2A/2B/2C/2D assume a case of “ResourceAllocation type 0”.

TABLE 7 Resource Block Resource System Bandwidth Assignment Bits BlockAssignment Bits in (RB) in DCI Format 0/1A DCI Format 1/2/2A/2B/2C/2D 65 6 15 7 8 25 9 13 50 11 17 75 12 19 100 13 25

Specifically, if a specific discovery resource unit (DRU) is defined by1 RB and a resource block allocation field of a DCI format 0, which ispreviously used for activating or deactivating a legacy SPS, is reusedto notify information on a discovery resource unit index (position), allof 100 discovery resource unit indexes (positions) can be notified using7 bits only among the total 13 bits of the resource block allocationfield (i.e., it is able to designate maximum 128 discovery resource unitindexes (positions)). In this case, i) the remaining bits (i.e., 6 bits)not used for notifying the information on the DRU index (position) canbe configured to be padded by a predetermined value (i.e., 0). Or, ii)the bits (i.e., 7 bits) configured (used) to notify the DRU index(position) can be configured to be repeatedly inputted (repetition &rate-matching) until the RBA fields are fully filled (sort of circularshift operation). Or, iii) the remaining bits not used for notifying theDRU index (position) information can be configured to be reserved.

As a different example, in case of reusing a resource block allocationfield of a specific DCI format, which is previously used for activatingor deactivating a legacy SPS to notify resource information related totransmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal), it is able to configure a D2D UE to finallyidentify the resource information related to transmission of the D2Dsignal (e.g., D2D discovery signal and/or D2D communication signal)using a result value, which is deducted by inputting a value of theresource allocation field of the signaled specific DCI format to apredefined function.

As a further different example, in a situation of FIG. 10, if a D2D UEindicates to perform single D2D discovery signal transmission only in adiscovery resource group (DRG), the remaining bits (i.e., 6 bits) notused for notifying the discovery resource unit index (position)information can also be configured for a usage of notifying an index(position) of a discovery subframe (DSF) in which actual D2D discoverysignal transmission is to be performed. In this case, 64 discoverysubframe indexes (positions) in total can be notified by the remaining 6bits not used for notifying the discovery resource unit index (position)information.

Or, the remaining bits (i.e., 6 bits) not used for notifying thediscovery resource unit index (position) information can also beconfigured for a usage of notifying a space (i.e., K) between a subframeposition (i.e., SF #N)) at which DCI information (or a message) relatedto the activation of transmission of a D2D discovery signal is receivedand a discovery subframe position (i.e., SF #(N+K)) at which actual D2Ddiscovery signal transmission is to be performed.

Or, the remaining bits (i.e., 6 bits) not used for notifying thediscovery resource unit index (position) information can also be used asa sort of timing offset information. If a D2D UE receives the offsetinformation (i.e., 01), the D2D UE calculates a sum with a differentoffset value (i.e., 02) signaled (configured) in advance, applies thesum value (i.e., “01+02”) from a subframe position (i.e., SF #N) atwhich DCI information (or message) related to activation of initiatingtransmission of a D2D discovery signal is received and may be then ableto identify a discovery subframe position (i.e., SF # (N+01+02)) atwhich actual D2D discovery signal transmission is to be performed.

Or, it may be able to configure timing offset value informationcorresponding to configuration values (states) of the remaining bits(i.e., 6 bits) not used for notifying the discovery resource unit index(position) information via predefined signaling/configuration. In thiscase, if a D2D UE receives bits corresponding to a specificconfiguration value, the D2D UE applies a timing offset value (i.e., 03)corresponding to the configuration value from a subframe positon (i.e.,SF #N) at which DCI information (or message) related to activation ofinitiating transmission of a D2D discovery signal is received and may bethen able to identify a discovery subframe position (i.e., SF # (N+03))at which actual D2D discovery signal transmission is to be performed.

As a further different example, it is able to configure resourceinformation (e.g., discovery resource unit index (position) information,discovery subframe index (position) information, etc.) related totransmission of a D2D discovery signal (e.g., D2D discovery signaland/or D2D communication signal) to be identified by a combination offields designated on a specific DCI format, which is previously used foractivating or deactivating a legacy SPS. The resource information can beefficiently notified using bits of which pluralities of fields arecombined. Moreover, the field combination information can be signaled orconfigured in advance or can be designated by a partial combination fromamong fields described in the following.

-   -   Carrier indicator    -   Flag for distinguishing format0 from format1A    -   Frequency hopping flag    -   Resource block allocation and hopping resource allocation    -   Modulation and coding scheme and redundancy version)    -   New data indicator)    -   TPC command for scheduled PUSCH)    -   Cyclic shift for DM RS (Demodulation Reference Signal) and OCC        (Orthogonal Cover Code) index    -   Uplink index    -   Downlink Assignment Index    -   Channel state information request    -   SRS request    -   Resource allocation type    -   Resource allocation header (resource allocation type 0/type 1    -   Resource block allocation    -   Modulation and coding scheme)    -   HARQ process number    -   Redundancy version    -   TPC command for PUCCH)    -   HARQ-ACK resource offset)    -   Localized/Distributed VRB assignment flag

When the field combination of the aforementioned usage is designated, i)it is able to configure (all or a part of) fields configured by a fixedvalue to notify activation/deactivation of a legacy SPS (refer to Table3 to Table 5) to be excluded. Or, ii) if a field configured by a fixedvalue to notify activation/deactivation of the legacy SPS is selected,it is able to configure the remaining bits, which are not configured bythe fixed value, to be used on the field only. When the fieldcombination of the aforementioned usage is designated, i) it is able toconfigure (all or a part of) fields configured by a fixed value tonotify activation/deactivation of initiation of transmitting a D2Ddiscovery signal (e.g., D2D discovery signal and/or D2D communicationsignal) to be excluded. Or, ii) if a field configured by a fixed valueto notify activation/deactivation of initiation of transmitting a D2Ddiscovery signal (e.g., D2D discovery signal and/or D2D communicationsignal) is selected, it is able to configure the remaining bits, whichare not configured by the fixed value, to be used on the field only.

As a further different example of the embodiment of the presentinvention, resource information related to transmission of a D2D signal(e.g., D2D discovery signal and/or D2D communication signal) can beconfigured to be identified by reinterpreting values of a fieldcombination designated in advance on a specific DCI format, which ispreviously used for activating or deactivating a legacy SPS, (accordingto a predefined rule). In this case, since it is able to sufficientlysecure the number of bits required for notifying the resourceinformation related to the transmission of the D2D signal (e.g., D2Ddiscovery signal and/or D2D communication signal), a D2D UE can controla PUSCH SPS operation of the D2D UE and a D2D discovery signal (e.g.,type 2 DS) transmission operation at the same time based on a (legacy)SPS C-RNTI without a process of receiving a separate RNTI.

Embodiment 3

According to embodiment 3 of the present invention, in a situation thata ProSe-related resource (e.g., number/position of D2D subframes) issemi-statically or statically configured, i) it is able to configureuplink scheduling information (UL grant) to be used as one selected fromthe group consisting of a) resource information related to transmissionof a D2D discovery signal, b) resource information related totransmission of a D2D communication signal and c) resource informationrelated to transmission of a WAN UL data (PUSCH) according to a downlinksubframe position at which uplink scheduling information (UL grant)related to transmission of uplink data channel (PUSCH) is received. Or,ii) it is able to configure resource allocation information on acorresponding UL DCI format or the UL DCI format to be used as oneselected from the group consisting of a) resource information related totransmission of a D2D discovery signal, b) resource information relatedto transmission of a D2D communication signal and c) resourceinformation related to transmission of a WAN UL data (PUSCH) accordingto an uplink subframe position at which UL scheduling information (ULgrant)-based uplink data channel (PUSCH) is actually transmitted.

According to the embodiment 3 of the present invention, if it isnecessary to receive uplink scheduling information (UL grant) at thetime of SF #N and transmit an uplink signal (or channel) at the time ofSF # (N+K) according to a predefined uplink HARQ timeline, a usage ofthe uplink scheduling information (UL grant) (or, the resourceallocation information on the UL DCI format or the UL DCI format) can beconfigured to be interpreted as a) resource information related totransmission of a D2D discovery signal, b) resource information relatedto transmission of a D2D communication signal or c) resource informationrelated to transmission of a WAN UL data (PUSCH) depending on whetherthe SF #(N+K) corresponds to a subframe configured for a usage oftransmitting a D2D discovery signal, a subframe configured for a usageof transmitting a D2D communication signal or a subframe configured fora usage of transmitting WAN UL data (PUSCH).

Embodiment 4

According to embodiment 4 of the present invention, in a situation thata ProSe-related resource (e.g., number/position of D2D subframes) issemi-statically or statically configured, if a specific DCI format,which is previously used for activating or deactivating a legacy SPS, isreused to notify activation or deactivation of initiation oftransmitting a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal) or notify resource information related totransmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal), it is able to configure values (refer to Table 3to Table 5) of partial fields, which are configured by a fixed value tonotify activation or deactivation of a legacy SPS on a specific DCIformat, to be identically maintained (i.e., field value configurationscapable of being used not only for a virtual CRC but also for a usage ofindicating activation and deactivation of the legacy SPS can berespectively reinterpreted (reused) to indicate activation anddeactivation of initiation of transmitting a D2D signal (e.g., D2Ddiscovery signal and/or D2D communication signal). Or, if a specific DCIformat is used for a usage of notifying activation or deactivation ofinitiation of transmitting a D2D signal (e.g., D2D discovery signaland/or D2D communication signal) or a usage of notifying resourceinformation related to transmission of a D2D signal (e.g., D2D discoverysignal and/or D2D communication signal), it is able to configure (all ora part of) the field value configurations for indicating activation ordeactivation of the legacy SPS to be redefined as an exceptional case.

In this case, as an example, if a DCI format 0, which is previously usedfor notifying activation/deactivation of a legacy SPS, is reused for theusage of notifying activation or deactivation of the initiation oftransmitting a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal) or the usage of notifying the resource informationrelated to the transmission of a D2D signal (e.g., D2D discovery signaland/or D2D communication signal), it is able to use a cyclic shift DM RSfield of the DCI format 0 (i.e., this is just an example and it may beextended to a different field), which is configured by a fixed value(‘000’ (i.e., refer to Table 3 to Table 5)) to notifyactivation/deactivation of the legacy SPS, in a manner of beingredefined (reinterpreted).

As a concrete example, if the cyclic shift DM RS field is configured bya value of ‘001’, it is considered as the DCI format 0 is used for theusage of notifying activation/deactivation of the legacy SPS (and/orlegacy SPS-related resource information). On the contrary, if the cyclicshift DM RS field is configured by a value of ‘010’, it can beconfigured as the DCI format 0 is used for the usage of notifyingactivation or deactivation of the initiation of transmitting a D2Dsignal (e.g., D2D discovery signal and/or D2D communication signal) orthe usage of notifying the resource information related to thetransmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal).

In addition, if the specific DCI format, which is previously used foractivating or deactivating the legacy SPS, is reused for the usage ofnotifying activation or deactivation of the initiation of transmitting aD2D signal (e.g., D2D discovery signal and/or D2D communication signal)or the usage of notifying the resource information related to thetransmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal), a part (or a combination) of fields of the DCIformat, which is configured by a fixed value (i.e., refer to Table 3 toTable 5) to notify activation/deactivation of the legacy SPS, can beredefined (or reinterpreted).

Table 8 shows an example of fields for checking PDCCH/EPDCCH including aspecific field for indicating SPS activation (and/or SPSactivation-related resource information) (hereinafter, case A) or aspecific field for indicating activation of transmission of a D2Ddiscovery signal/D2D communication signal (and/or resource activationinformation related to transmission of a D2D discovery signal/D2Dcommunication signal) (hereinafter, case B).

TABLE 8 DCI format 0 DCI format 1/1A DCI format 2/2A/2B/2C/2D TPCcommand for [01]: CASE #A N/A N/A scheduled PUSCH [10]: CASE #B Cyclicshift DM RS [001]: CASE #A N/A N/A [010]: CASE #B Modulation and coding[‘MSB = 0’]: N/A N/A scheme and redundancy CASE #A, CASE #B version HARQprocess number N/A <FDD> <FDD> [001]: CASE #A [001]: CASE #A [010]: CASE#B [010]: CASE #B <TDD> <TDD> [0001]: CASE #A [0001]: CASE #A [0010]:CASE #B [0010]: CASE #B Modulation and coding N/A [‘MSB = 0’]: For theenabled transport block: scheme CASE #A, CASE #B [‘MSB = 0’]: CASE #A,CASE #B Redundancy version N/A [01]: CASE #A For the enabled transportblock: [10]: CASE #B [01]: CASE #A [10]: CASE #B

Table 9 shows an example of fields for checking PDCCH/EPDCCH including aspecific field for indicating SPS deactivation (and/or SPSdeactivation-related resource information) (hereinafter, case A) or aspecific field for indicating deactivation of transmission of a D2Ddiscovery signal/D2D communication signal (and/or resource deactivationinformation related to transmission of a D2D discovery signal/D2Dcommunication signal) (hereinafter, case #B).

TABLE 9 DCI format 0 DCI format 1A TPC command for scheduled [01]: CASE#A N/A PUSCH [10]: CASE #B Cyclic shift DM RS [001]: CASE #A N/A [010]:CASE #B Modulation and coding scheme [11111]: N/A and redundancy versionCASE #A, CASE #B Resource block assignment and [Set to all ‘1’s]: N/Ahopping resource allocation CASE #A, CASE #B HARQ process number N/A<FDD> [001]: CASE #A [010]: CASE #B <TDD> [0001]: CASE #A [0010]: CASE#B Modulation and coding scheme N/A [11111]: CASE #A, CASE #B Redundancyversion N/A [01]: CASE #A [10]: CASE #B Resource block assignment N/A[Set to all ‘1’s]: CASE #A, CASE #B

Hence, in Table 8 and Table 9, it is able to configure a DCI format tonotify whether the DCI format is used for a) the usage of activating ordeactivating the legacy SPS (and/or legacy SPS-related resourceinformation) (i.e., case #A) or b) the usage of notifying activation ordeactivation of the initiation of transmitting a D2D signal (e.g., D2Ddiscovery signal and/or D2D communication signal) or the usage ofnotifying the resource information related to the transmission of a D2Dsignal (e.g., D2D discovery signal and/or D2D communication signal)(i.e., case #B).

In this case, it is able to notify whether the specific DCI format isused for a) the usage of activating or deactivating the legacy SPS(and/or legacy SPS-related resource information) (i.e., case #A) or b)the usage of notifying activation or deactivation of the initiation oftransmitting a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal) or the usage of notifying the resource informationrelated to the transmission of a D2D signal (e.g., D2D discovery signaland/or D2D communication signal) (i.e., case #B) using a combination ofa part of (or all) fields listed on Table 8 and Table 9 only. Or, eachfield listed on Table 8 and Table 9 is able to be independently used(interpreted) for notifying whether the specific DCI format is used fora) the usage of activating or deactivating the legacy SPS (and/or legacySPS-related resource information) (i.e., case #A) or b) the usage ofnotifying activation or deactivation of the initiation of transmitting aD2D signal (e.g., D2D discovery signal and/or D2D communication signal)or the usage of notifying the resource information related to thetransmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal) (i.e., case #B).

In this case, according to a method of the case #B, since an amount ofrequired bits is not that big when a simple control procedure-based D2DProSe implementation is considered, it is able to configure (a part of,all or the rest of) values of (different or identical) predefined fieldsto be additionally configured by a fixed value as well as partial fieldsconfigured by a fixed value to notify activation/deactivation of alegacy SPS on a specific DCI format.

And, as an example, it is able to configure a D2D UE to detect a DCIformat, which is transmitted to notify resource information related totransmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal), and/or a DCI format, which is transmitted tonotify activation or deactivation of initiation of transmitting a D2Dsignal (e.g., D2D discovery signal and/or D2D communication signal),based on a predefined or signaled SPS C-RNTI of the D2D UE, C-RNTI,temporary C-RNTI or D2D-RNTI newly configured or signaled for a D2Dusage.

The aforementioned embodiments of the present invention (i.e.,embodiment 1 to embodiment 4) can also be extensively applied to a caseof reusing other DCI formats (e.g., DCI format 1B, DCI format 1C, DCIformat 3, DCI format 3A and DCI format 4) instead of a specific DCIformat previously used for notifying activation or deactivation of alegacy SPS or a case of using partial fields of other DCI format in amanner of being modified/aggregated/reinterpreted to notify activationor deactivation of initiation of transmitting a D2D signal (e.g., D2Ddiscovery signal and/or D2D communication signal) or notify resourceinformation related to transmission of a D2D signal (e.g., D2D discoverysignal and/or D2D communication signal).

In the aforementioned embodiments of the present invention, a DCIformat, which is transmitted to notify activation or deactivation ofinitiation of transmitting a D2D signal (e.g., D2D discovery signaland/or D2D communication signal), or a DCI format, which is transmittedto notify resource information related to transmission of a D2D signal(e.g., D2D discovery signal and/or D2D communication signal), can beinterpreted as being transmitted by a serving base station of a D2D UEor a D2D cluster head.

And, the aforementioned embodiments of the present invention can also beextensively applied to a case that ProSe-related resources (e.g.,number/position of D2D subframes) are dynamically re-changed through apredefined physical layer channel (e.g., PDCCH, (E)PDCCH, PDSCH) or ahigher layer signal.

Moreover, the aforementioned embodiments of the present invention canalso be extensively applied to a case that all D2D UEs participating inD2D ProSe perform D2D communication at the outside of network coverage(D2D communication outside network coverage (for public safety only)).

And, in the aforementioned embodiments of the present invention, theremaining bits except i) bits used for notifying activation ordeactivation of initiation of transmitting a D2D signal (e.g., D2Ddiscovery signal and/or D2D communication signal) ii) bits configured bya fixed value to notify activation or deactivation of initiation oftransmitting a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal), iii) bits used for notifying resource information(e.g., discovery resource unit index (or position) information,discovery subframe index (or position) information, etc. related totransmission of a D2D signal (e.g., D2D discovery signal and/or D2Dcommunication signal), iv) bits configured by a fixed value to notifyactivation/deactivation of a legacy SPS among total bits on a specificDCI format can be configured to be padded by a predefined value (i.e.,0) or reserved.

The aforementioned embodiments of the present invention (i.e., at leastone of the embodiment 1 to the embodiment 4) can be configured to berestrictively applied to a predefined situation only. For example, it isable to configure the aforementioned embodiments to be restrictivelyapplied to at least one case selected from the group consisting of i) acase that a D2D ProSe mode is configured, ii) a case that both an SPSmode and the D2D ProSe are configured at the same time, iii) a case thata specific service type (e.g., a public safety-related D2D service, acommercial D2D service, a groupcast D2D service, a unicast D2D service,a broadcast D2D service, a multicast D2D service, etc.) of D2D ProSe isperformed, iv) a case that a D2D discovery operation is performed, v) acase that a D2D communication operation is performed, vi) a case that adecoding operation of a D2D discovery signal is performed, vii) a casethat a decoding operation of a D2D communication data is performed,viii) a case that a D2D UE is aware of identification information ofinterested D2D UEs, and ix) a case that a D2D UE is not aware ofidentification information of interested D2D UEs.

Moreover, since the aforementioned embodiments are able to be includedas one of methods of implementing the present invention, it is apparentthat the embodiments are capable of being regarded as a sort of proposedschemes. Each of the aforementioned proposed schemes can beindependently implemented and can be implemented in a manner of beingcombined (aggregated) with each other.

Moreover, the aforementioned embodiments of the present invention can beextensively applied to a case that D2D ProSe is performed underenvironment to which a carrier aggregation (CA) scheme is applied.

And, a D2D UE can receive information on rules/configurations of theembodiments of the present invention, information on whether to applythe rules/configurations and the like through a predefined signal (e.g.,a physical layer or a higher layer signal).

And, as an example, it may be able to configure the aforementionedembodiments of the present invention to be restrictively applied onlywhen a specific D2D UE is aware of DS transmission resource positions ofinterested D2D UEs and/or when a specific D2D UE is not aware of DStransmission resource positions of interested D2D UEs. In this case,when the specific D2D UE is aware of the DS transmission resourcepositions of the interested D2D UEs or the specific D2D UE is not awareof the DS transmission resource positions of the interested D2D UEs, itmay corresponds to one selected from the group consisting of i) a casethat the specific D2D UE is aware of identifiers of the interested D2DUEs and becomes aware of the DS transmission resource positions of theinterested D2D UEs through a predefined function (e.g., a DStransmission resource position of a D2D UE is defined by a function of aUE identifier), ii) a case that the specific D2D UE is aware of theidentifiers of the interested D2D UEs in a manner that a DS transmissionresource position of a D2D UE is affected by other elements (orparameters) except an identifier of the D2D UE but the specific D2D UEis not aware of the DS transmission resource positons of the interestedD2D UEs and iii) a case that the specific D2D UE is not aware of theidentifiers of the interested D2D UEs but a discovery applicationdesigned in advance informs the specific D2D UE of D2D UEs near thespecific D2D UE in a manner of appropriately discovering and summarizingthe D2D UEs near the specific D2D UE.

In addition, the proposed methods can be extensively applied to a casethat a discovery procedure is defined as “A Discovery Procedure WhereResources for Discovery Signal Transmission Are Allocated on A Non-UESpecific Basis (e.g., Resources Can Be for All UEs or Group of UEs)” or“A Discovery Procedure Where Resources for Discovery Signal TransmissionAre Allocated on A Per UE Specific Basis (e.g., Resources Are Allocatedfor Each Specific Transmission Instance of Discovery Signals orResources Are Semi-Persistently Allocated for Discovery SignalTransmission)”.

And, the aforementioned embodiments of the present invention can also beextensively applied to a case that a D2D UE detects discovery signals ofinterested D2D UEs only (i.e., closed discovery procedure) or a casethat a D2D UE detects all discovery signals of other D2D UEs capable ofbeing detected irrespective of whether or not the D2D UE is interestedin the DSs of other D2D UEs (i.e., open discovery procedure.

FIG. 11 is a diagram for a base station and a user equipment capable ofbeing applied to an embodiment of the present invention.

If a relay is included in a wireless communication system, communicationis performed between a base station and the relay in backhaul link andcommunication is performed between the relay and a user equipment inaccess link. Hence, the base station and the user equipment shown in thedrawing can be replaced with the relay in accordance with a situation.

Referring to FIG. 11, a wireless communication system includes a basestation (BS) 110 and a user equipment (UE) 120. The BS 110 includes aprocessor 112, a memory 114 and a radio frequency (RF) unit 116. Theprocessor 112 can be configured to implement the proposed functions,processes and/or methods. The memory 114 is connected with the processor112 and then stores various kinds of information associated with anoperation of the processor 112. The RF unit 116 is connected with theprocessor 112 and transmits and/or receives a radio signal. The userequipment 120 includes a processor 122, a memory 124 and a radiofrequency (RF) unit 126. The processor 122 can be configured toimplement the proposed functions, processes and/or methods. The memory124 is connected with the processor 122 and then stores various kinds ofinformation associated with an operation of the processor 122. The RFunit 126 is connected with the processor 122 and transmits and/orreceives a radio signal. The base station 110 and/or the user equipment120 may have a single antenna or multiple antennas.

The above-described embodiments correspond to combinations of elementsand features of the present invention in prescribed forms. And, therespective elements or features may be considered as selective unlessthey are explicitly mentioned. Each of the elements or features can beimplemented in a form failing to be combined with other elements orfeatures. Moreover, it is able to implement an embodiment of the presentinvention by combining elements and/or features together in part. Asequence of operations explained for each embodiment of the presentinvention can be modified. Some configurations or features of oneembodiment can be included in another embodiment or can be substitutedfor corresponding configurations or features of another embodiment. And,it is apparently understandable that an embodiment is configured bycombining claims failing to have relation of explicit citation in theappended claims together or can be included as new claims by amendmentafter filing an application.

In this disclosure, a specific operation explained as performed by abase station may be performed by an upper node of the base station insome cases. In particular, in a network constructed with a plurality ofnetwork nodes including a base station, it is apparent that variousoperations performed for communication with a user equipment can beperformed by a base station or other networks except the base station.‘Base station (BS)’ may be substituted with such a terminology as afixed station, a Node B, an eNode B (eNB), an access point (AP) and thelike.

Embodiments of the present invention can be implemented using variousmeans. For instance, embodiments of the present invention can beimplemented using hardware, firmware, software and/or any combinationsthereof. In the implementation by hardware, a method according to eachembodiment of the present invention can be implemented by at least oneselected from the group consisting of ASICs (application specificintegrated circuits), DSPs (digital signal processors), DSPDs (digitalsignal processing devices), PLDs (programmable logic devices), FPGAs(field programmable gate arrays), processor, controller,microcontroller, microprocessor and the like.

In case of the implementation by firmware or software, a methodaccording to each embodiment of the present invention can be implementedby modules, procedures, and/or functions for performing theabove-explained functions or operations. Software code is stored in amemory unit and is then drivable by a processor.

The memory unit is provided within or outside the processor to exchangedata with the processor through the various means known in public.

While the present invention has been described and illustrated hereinwith reference to the preferred embodiments thereof, it will be apparentto those skilled in the art that various modifications and variationscan be made therein without departing from the spirit and scope of theinvention. Thus, it is intended that the present invention covers themodifications and variations of this invention that come within thescope of the appended claims and their equivalents.

Although the method of transmitting and receiving control informationfor D2D (device-to-device) communication in a wireless communicationsystem and an apparatus therefor are described centering on examplesapplied to 3GPP LTE system, it may be applicable to various wirelesscommunication systems as well as to the 3GPP LTE system.

What is claimed is:
 1. A method of transmitting uplink data, by a userequipment (UE) in a wireless communication system, the methodcomprising: receiving a physical downlink control channel (PDCCH), whichis scrambled with a semi-persistent scheduling (SPS)—radio networktemporary identifier (RNTI) (SPS-RNTI) and includes a downlink controlinformation (DCI) format 0; validating an SPS uplink schedulingassignment based on the received PDCCH; and transmitting the uplink databased on the SPS uplink scheduling assignment, wherein the validatingcomprises: if the SPS-RNTI is not for Proximity Services (ProSe)communication, checking if two bits in a first field in the DCI format 0are set to ‘00’; checking if three bits in a second field in the DCIformat 0 are set to ‘000’; and checking if a most significant bit (MSB)in a third field in the DCI format 0 is set to ‘0’, else if the SPS-RNTIis for the ProSe communication, checking if the two bits in the firstfield in the DCI format 0 are set to ‘00’, and checking if the MSB inthe third field in the DCI format 0 is set to ‘0’, and wherein if theSPS-RNTI is for the ProSe communication, the three bits in the secondfield are used for indicating a resource allocation for the ProSecommunication.
 2. The method of claim 1, wherein if the SPS-RNTI is forthe ProSe communication, the three bits in the second field are used forindicating that the DCI format 0 is used for the resource allocation forthe ProSe communication.
 3. The method of claim 1, wherein the firstfield in the DCI format 0 is related to a transmit power control (TPC)command for a physical uplink shared channel (PUSCH).
 4. The method ofclaim 1, wherein the second field in the DCI format 0 is related to acyclic shift demodulation reference signal (DM RS) if the SPS-RNTI isnot for the ProSe communication.
 5. The method of claim 1, wherein thethird field in the DCI format 0 is related to a modulation and codingscheme and redundancy version.
 6. The method of claim 1, wherein if theSPS-RNTI is not for the ProSe communication, the UE validates the SPSuplink scheduling assignment only if all of the following conditions aremet: the two bits in the first field in the DCI format 0 are set to‘00’; the three bits in the second field in the DCI format 0 are set to‘000’; and the MSB in the third field in the DCI format 0 is set to ‘0’.7. The method of claim 1, wherein if the SPS-RNTI is for the ProSecommunication, the UE validates the SPS uplink scheduling assignmentonly if all of the following conditions are met: the two bits in thefirst field in the DCI format 0 are set to ‘00’, and the MSB in thethird field in the DCI format 0 is set to ‘0’.
 8. The method of claim 1,wherein a size of the DCI format 0 is the same for when the SPS-RNTI isfor the ProSe communication and for when the SPS-RNTI is not for theProSe communication.
 9. The method of claim 1, wherein the first fieldin the DCI format 0 is immediately followed by the second field in theDCI format 0, and the second field in the DCI format 0 is immediatelyfollowed by the third field in the DCI format
 0. 10. The method of claim1, wherein the second field is a partial field of the DCI format
 0. 11.The method of claim 10, wherein the partial field is reinterpreted whenthe SPS-RNTI is for the ProSe communication.
 12. The method of claim 1,wherein the SPS-RNTI for the UE is different from an uplink SPS—cellradio network temporary identifier (C-RNTI).
 13. The method of claim 1,wherein the first field, the second field and the third field areincluded in a table including special fields for SPS activationPDCCH/enhanced PDCCH (EPDCCH) validation.
 14. A communication device foruse in a wireless communication system, the device comprising: a memory;and a processor, wherein the processor is configured to: receive aphysical downlink control channel (PDCCH), which is scrambled with asemi-persistent scheduling (SPS)—radio network temporary identifier(RNTI) (SPS-RNTI) and includes a downlink control information (DCI)format 0; validate an SPS uplink scheduling assignment based on thereceived PDCCH; and transmit uplink data based on the SPS uplinkscheduling assignment, wherein the validating comprises: if the SPS-RNTIis not for Proximity Services (ProSe) communication, checking if twobits in a first field in the DCI format 0 are set to ‘00’; checking ifthree bits in a second field in the DCI format 0 are set to ‘000’; andchecking if a most significant bit (MSB) in a third field in the DCIformat 0 is set to ‘0’, else if the SPS-RNTI is for the ProSecommunication, checking if the two bits in the first field in the DCIformat 0 are set to ‘00’, and checking if the MSB in the third field inthe DCI format 0 is set to ‘0’, and wherein if the SPS-RNTI is for theProSe communication, the three bits in the second field are used forindicating a resource allocation for the ProSe communication.
 15. Thedevice of claim 14, wherein if the SPS-RNTI is for the ProSecommunication, the three bits in the second field are used forindicating that the DCI format 0 is used for the resource allocation forthe ProSe communication.
 16. The device of claim 14, wherein the firstfield in the DCI format 0 is related to a transmit power control (TPC)command for a physical uplink shared channel (PUSCH).
 17. The device ofclaim 14, wherein the second field in the DCI format 0 is related to acyclic shift demodulation reference signal (DM RS) if the SPS-RNTI isnot for the ProSe communication.
 18. The device of claim 14, wherein thethird field in the DCI format 0 is related to a modulation and codingscheme and redundancy version.
 19. The device of claim 14, wherein ifthe SPS-RNTI is not for the ProSe communication, the UE validates theSPS uplink scheduling assignment only if all of the following conditionsare met: the two bits in the first field in the DCI format 0 are set to‘00’; the three bits in the second field in the DCI format 0 are set to‘000’; and the MSB in the third field in the DCI format 0 is set to ‘0’.20. The device of claim 14, wherein if the SPS-RNTI is for the ProSecommunication, the UE validates the SPS uplink scheduling assignmentonly if all of the following conditions are met: the two bits in thefirst field in the DCI format 0 are set to ‘00’, and the MSB in thethird field in the DCI format 0 is set to ‘0’.
 21. The device of claim14, wherein a size of the DCI format 0 is the same regardless of whetherthe SPS_RNTI is for the ProSe communication.
 22. The device of claim 14,wherein the first field in the DCI format 0 is immediately followed bythe second field in the DCI format 0, and the second field in the DCIformat 0 is immediately followed by the third field in the DCI format 0.23. The device of claim 14, wherein the second field is a partial fieldof the DCI format
 0. 24. The device of claim 23, wherein the partialfield is reinterpreted when the SPS-RNTI is for the ProSe communication.25. The device of claim 14, wherein the SPS-RNTI for the UE is differentfrom an uplink SPS—cell radio network temporary identifier (C-RNTI). 26.The device of claim 14, wherein the first field, the second field andthe third field are included in a table including special fields for SPSactivation PDCCH/enhanced PDCCH (EPDCCH) validation.